FIG. 5.

MTKDEL fails to bind the signaling proteins ShcA, PI3K, and PLC-γ1. (A) The protein binding properties of each of the mutants shown in Fig. 3 were determined by immunoprecipitating the MT present in equal volumes of lysate from cells expressing each of the mutants, separating it by SDS-PAGE, and Western blotting. The antibody reactivity used to probe each blot is shown above each panel, and the mutant used is indicated above each lane on the top panel. The migration position of each detected polypeptide species is shown to the right. (B) Kinase activities present in MT immunoprecipitates. Each of the MT species shown in panel A was immunoprecipitated and incubated with [γ-³²P]ATP, separated by SDS-PAGE, and autoradiographed. The mutant used is indicated above each lane, and the migration positions of MT and its associated proteins are indicated to the right.